Please check the review configuration to see if the type of field being used to collect the ULN value is 'Numeric'.
If the 'Numeric' type field is being used, then this is the cause of the error as this type of field has a maximum value of 2147483647 due to it being an int32 value type. So, if the entered ULN exceeds this maximum value, you will see the error.
If you using the 'Text' type field to collect the ULN, you will not encounter this error.